Syrian hamsters will be used to study the function of abnormal retinal projections created as a result of neonatal surgery. A surgical technique has been devised which reliably produces retinal projections to the medial geniculate or the ventrobasal nucleus; these structures normally receive auditory and somatosensory input, respectively, but not visual input. Standard electrophysiological techniques will be used to determine if the anomalous projections are capable of driving thalamic neurons or cortical neurons to which the thalamic cells project, when the hamsters are subjected to visual stimulation. Assuming a positive result, additional electrophysiological studies will be undertaken to determine the visual receptive field properties of single neurons receiving anomalous visual input, and the degree of retinotopic organization present in the experimentally induced visual pathways. The results of these studies will have fundamental implications for the development of orderly connections and the organization of single unit receptive field properties in normal animals, and are of potential value in the treatment of central nervous system lesions in man.